1. Field of the Invention
The present invention relates to an electronic control device, and more particularly, to an electronic control device used for an electric power steering apparatus for assist-urging a steering apparatus of a vehicle by a torque of an electric power motor.
2. Description of the Related Art
Up to now, there has been known an electronic control device in which a semiconductor switching device (for example, a FET) serving as a power device is mounted to a metal board and a connection member for electrically connecting the metal board with parts located outside the metal board is attached onto the metal board.
For example, a conventional electronic control device includes a power board in which a bridge circuit having semiconductor switching devices for switching a current of an electric power motor is contained, a housing in which a conductive plate and the like which are inserted into an insulating resin by molding and large-current parts are contained, a control board in which small current parts such as microcomputers are contained, a connection member for electrically connecting the power board, the housing, and the control board with one another, a heat sink brought into close contact with the power board, and a case which is provided to cover the power board, the housing, and the control board, formed by press molding using a metal plate, and attached to the heat sink (see, for example, JP 3644835 B).
However, the conventional technology has the following problems.
The electronic control device described in JP 3644835 B requires the metal board containing the semiconductor switching devices. The connection member is fixed onto the metal board so as to prevent the connection member from floating at the time of soldering. As a result, there is a problem that the number of parts increases to increase a size of the electronic control device and a cost thereof.
An impact force caused when the connection member is fixed onto the power board is transferred to parts such as the semiconductor switching devices which are located on the power board before soldering, so a displacement in position of each of the parts occurs. Therefore, there is a problem that the reliability of soldering bonding of the parts mounted to the power board reduces.